using System;

using System.Linq;

using System.Threading;

public class Program

{

    public static void Main()

    {

        Console.WriteLine($"Main thread {Thread.CurrentThread.ManagedThreadId}");

        Enumerable.Range(0, 1_000_000).Where(x => { Console.WriteLine($"{x} th: {Thread.CurrentThread.ManagedThreadId}") ;  return x == 0; }).AsParallel().First();

    }

}